GPIB-USB-HS+ Timeout Setting

[ooth]

Is the a reason why you can only set the timeout for a GPIB-USB to 10, 30, 1000, 3000, 10000, 30000, ...etc and nothing in between those values?

I tried in both MAX and LabVIEW and both returned with the same restricted values. I'm using MAX V21.5.

[RTSLVU]

I believe those settings only effect the VISA Test Panel itself.

The VISA Test Panel is just a simple interface for troubleshooting instrument connectivity. So they only put a few common values in the Timeout selection dropdown.

You can use the VISA Timeout Property Node to set the VISA Timeout to anything you want in your program.

[ooth]

Well that isn’t a drop down selection. If you type in 1001 and hit apply it changes it to 3000. More importantly I found that if you use a VISA timeout property node and write 2000 it will execute without an error. But if you immediately wire a read timeout it will return 3000. The funny thing is this only happens when the VISA being used is with a GPIB-USB. If the connection is say just a USB then it will take any value you set it.

[ooth]

Here's the timeout property nodes used to set 2000ms. In the top case that uses the GPIB-USB it looks like the write 2000ms works without an error but when you read the timeout it is 3000ms. In the bottom case the instrument is connected via USB and 2000ms is indeed set. FYI both instruments are Agilent network analyzers. The top case is an older model that does not have USB and only has a GPIB port.

[RTSLVU]

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@ooth wrote:

Well that isn’t a drop down selection.

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Whatever, I don't think my semantics is the issue here...

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@ooth wrote:

If you type in 1001 and hit apply it changes it to 3000. More importantly I found that if you use a VISA timeout property node and write 2000 it will execute without an error. But if you immediately wire a read timeout it will return 3000. The funny thing is this only happens when the VISA being used is with a GPIB-USB. If the connection is say just a USB then it will take any value you set it.

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Frankly I don't understand the issue as in almost two decades of using VISA with instruments on GPIB and any other interface I have never needed an exact Timeout period. 

In fact the only time the Timeout was ever an issue was getting a "Timeout expired" error when dealing with serial communications.

As long as it was set higher than it took to receive all the data it was fine.

Is there some reason you need a specific timeout period?

[ooth]

My program re-sends the command twice if there is a timeout. Well the default of 3sec kicked that time up to 9sec total (first timeout then 2 retries) and it would look like something hung up to the operator. So I went to reduce the timeout and was surprised that I could only pick 1sec. And I was a little concerned giving the instrument only 1sec to do the measurement. But oh well that's what I'm going to have to set it to.

I just wanted to ask the community why GPIB-USB only has certain timeout values.

[Kyle97330]

I don't know why it has the timeouts it does, but you should be able to string together multiple reads with short timeouts to effectively be one longer timeout.  Like, if you want a 500 ms timeout, you could try with a 30 ms timeout 16 or 17 times in a row.

[ooth]

Thanks Kyle. I will try doing that.